🚀 go-pugleaf

In article <1992Dec15.225304.11571@porthos.cc.bellcore.com>, bhatia@bigcat.bellcore.com (Raman Bhatia) writes:
|> In article <1992Dec14.181725@roper.mc.ti.com>, a722756@roper.mc.ti.com (W. Donald Rolph) writes:
|> |> 
|> |> This is by no means a trivial question.  You must first ask the class of FEA to
|> .......
|> |>  
|> |> It is also imperative that you have  a good mesh generator and graphical post
|> |> processor.  The difference between a good mesh generator and an ok mesh generator
|> |> is about 20X in productivity.
|> ........
|> |> 
|> |> A typical system ight cost the following (rough costs):
|> |>   
|> |>      1)  FEA program $5K - $10K year
|> |> 
|> |>      2)  Mesh generator $10K yr
|> |> 
|> |>      3)  Workstation:  $25K
|> |>  
|> |>      4)  color postscript printer $5K to $10K
|> |> 
|> |> This is nearly a 1/3 cost reduction and 10,000 performance improvement over the
|> |> system I put together is 1983!
|> |> 
|> |> 
|> |> -- 
|> |> 
|> |> Regards.
|> |>  
|> |> Don Rolph  a722756@pan.mc.ti.com WD3 MS10-13 (508)-699-1263
|> 
|> Thanks for a very informative post. Here's another question. What are
|> the latest in Mesh Generation techniques? 
|> 
|> The last time I dabbed in FEM, the finite-octree (w Delaunay triangulation) 
|> appeared the most promising but there were some concerns about robustness. 
|> I know that companies like PDA engineering (developers of PATRAN) were 
|> looking at "paving". What is the current status of these two techniques, 
|> and are there any new ones out there (AI approaches etc.)?
|> 
|> Raman Bhatia (bhatia@bigcat.bellcore.com)

I have an interesting proof that show that the triangularization schemes all
violate controllability theory at any given point in the model.  The effect is
that in 3D, with typcial dimensions in orthoganoal directions which have
significantly different scales (1.4 in thick by 5 inches wide by 20 inches long),
the triangularizations schemes produce highly unsatisfactory meshes for many
classes of problems, particularly nonlinear problems.  It is interesting to note
the CFd codes are gradually adopting Laplacian mesh generation schemes, schemes
which were popular as early as 1960 for fea.  It should be noted that CFD can be
very suseptible to poor meshes, and perhaps there is a message here!  

I have simplistic proof which suggests that Laplacian mapping produces the
"optimal mesh" fgor certain classes of problems, based on the givven mesh density
provided as input.  I also have s ample program which generates hexahedral meshes
off an arbitray boundary rep trimmed nurb solid model, demonstrating that the
technogy is feasible, and the input is not overly burdensome.
-- 

Regards.
 
Don Rolph  a722756@pan.mc.ti.com WD3 MS10-13 (508)-699-1263